Urinary incontinence is a dysfunction of the bladder's ability to securely retain urine until an individual intends to void. Causes for urinary incontinence are many and affect all age groups, but tends to be more prevalent in females and the elderly. The major forms of incontinence are stress incontinence, psychogenic incontinence, and trauma, typically surgical trauma to the vesicle neck. The market for amelioration of urinary incontinence is currently estimated at about 4% of the population and growing due to population shifts toward longer lifespans. At the present time, the costs related to urinary incontinence are estimated at between $1.8 and $10 billion in direct and indirect costs.
Current methods for treating urinary incontinence are pharmacological, surgical, behavioral, and prosthetic implant devices. The least intrusive treatment that can achieve desired results is always recommended. However, each of the existing treatments have limitations and drawbacks.
Several surgical procedures and devices for controlling urinary incontinence have been developed and tried with varying degrees of success. Examples of these include bladder suspension procedures, injection of collagen or passively inert constrictive materials procedures, and various combinations of these.
Behavioral treatment is useful in cases of minor dysfunction, while exercises can help minimize the effects in stress incontinence. Injectible implants of collagen have proven to be successful in mild cases, but are of limited long term use as the collagen is absorbed by the body over a relatively short period of time and must constantly be replaced.
The use of a long term prosthetic device has, historically, been the least desirable as these devices can cause irritation to the of the urethra and ultimately tissue necrosis if the prosthetic device causes circulatory insufficiency. In addition, the application of the obturating collars of some older devices required that the urethra be severed and reattached, further complicating the surgical procedure and causing additional trauma to the tissue.
Prosthetic devices based on the compression of the urethra at a given point are known and disclosed in, for example, “Treatment of urinary incontinence by implantable prosthetic sphincter,” by Bradley and Timm, Urology, 1:252 (1973); “Treatment of post-prostatectomy urinary incontinence using a gel prostheses”, by Kaufman, Brit. J. Urol., 45:646 (1973) and “Treatment of post-prostatectomy urinary incontinence using a silicon gel prostheses”, Brit, J Urol, 48:646 (1973).
In the practice of plastic and reconstructive surgery, inert materials have frequently been implanted to fill in defects or augment weakened tissue. These have been fabricated from a variety of materials and have been implanted using several techniques. Certain very small particle species compounded in a lubricious material have been implanted by subcutaneous injection for both soft and hard tissue augmentation. However, undesirable subsequent particle migration and granulomatous reactions have commonly resulted. This is well documented with such materials as polytetrafluoroethylene (PTFE) particles of very small diameter (>90% with a diameter <30 microns) in glycerin. One such product includes PTFE particles suspended in glycerin with a minor amount of polysorbate and is available under the name Polytef® (Mentor Corp. of California). This is discussed, for example, in Malizia, et al., JAMA, Volume 251, No, 24, pp. 3277-3281 (1984).
U.S. Pat. No. 4,773,393 (the '393 patent) relates to an apparatus for hypodermically implanting a genitourinary prosthesis comprising an extensible, inflatable tissue expanding containment membrane to be located in the proximal periurethral tissues to add bulk to these tissues and thereby overcome urinary incontinence by means of localized, controlled tissue volume increase. In column 1, reference is made to the aforementioned JAMA article co-authored by a co-patentee of the '393 patent, Anthony A. Malizia, with respect to the widespread migration of Polytef® particles along with granulomas. The invention of the '393 patent is said to obviate these problems by providing a prosthesis comprising an elastomerical biocompatible containment membrane into which a biomeric fluid or suspended particulate matter such as TEFLON particles is percutaneously injected to inflate the membrane.
The use of very small diameter particulate spheres (approximately 1-2.0 microns) or small diameter elongated fibrils, (generally 1-20 microns in diameter) of various materials such as cross-linked collagen or synthetic polymers suspended in an aqueous medium to which a biocompatible fluid lubricant has been added as an injectible implant composition is disclosed in U.S. Pat. No. 4,803,075. While these materials create immediate augmentation, the result is generally short-lived as the material also has a tendency to migrate and/or be reabsorbed from the injection site by the host tissue.
Recently, three companies have indicated in published reports their intent to enter the market for treatment of urinary incontinence with an injectible material. Mentor Corporation has received limited approval from the FDA for use of their injectible material, “Urethrin”, in treating incontinent male post-prostatectomy patients. Previous published reports stated that C. R. Bard, Inc, and Collagen Corporation were developing an incontinence treatment called “Contigen Bard Collagen Implant,” understood to be Collagen Corporation's “Contigen” injectible bovine collagen material. Subsequently, it was reported that: C. R. Bard is also evaluating for urinary incontinence treatment a product called “Hylagel-Muscle” which is said to be based upon technology disclosed in U.S. Pat. No. 5,099,013 directed to modifying naturally occurring hyaluronan “to form three-dimensional sponge-like matrixes in the form of high molecular mass fluids, gels and solids that can separate tissue, cells, and molecules.”
Artificial sphincters have been advanced in the prior art and the primary ones in use utilize an inflatable cuff surrounding a conduit to obturate material flow. In creating the localized pressure necessary to overcome the material back pressures, the cuff type devices also tend to obstruct the normal flow of blood in the conduit walls, and thus long term usage of cuff-type artificial sphincters is not viable. The continuous ring of pressure without adequate blood flow can result in scarring and localized tissue damage.
A type of a magnetically actuated artificial sphincter is disclosed in U.S. Pat. No. 3,926,175 showing a cuff having a section that is actuated by magnetic force to press against a conduit around which the cuff is placed. An external electromagnet is utilized for providing the force, and thus the device is not totally implantable, and is made so it will snap to a locked position and must be snapped back to an open position. While the device is made to apply forces only on two opposite sides of the conduit that it is surrounding, rather than in a noose-like complete ring, in order to prevent necrosis, the unit is still difficult to operate, and varying the closing pressure is difficult because the magnet used is for actuation of an over center actuating device.
U.S. Pat. No. 4,024,855 discloses a magnetic filament which may be implanted in the form of a pair of coils on opposite sides of a body tube such as a urethra. Both coils can be permanent magnet materials, or one can be a permanent magnet and the other a filament that has magnetic properties. The coils that are implanted are polarized so that they attract each other for the purposes of pinching the conduit or urethra closed. Then, in order to open the body conduit it is necessary to provide an external unit that creates a magnetic field which alters the polarity of the implanted coils so that the coils repel each other to open the tube. When drainage is over, the external power unit is used to return the implanted coils to their original polarity. It can be seen that such devices have limitations in the force that can be generated, and require the use of external controls for operation. Further, as a practical matter, controlling the pressure on the body conduit using these devices is so that leakage or dripping do not occur. Also, the coils can cause closure which is too tight and thus, can cause damage to the tissue as well.
A magnetically actuated device for controlling a tube that carries fluid flow to or from different organs of the body of a human is disclosed in U.S. Pat. No. 4,053,952 (the '952 patent). This device uses a type of valve arrangement which has a coil with oppositely facing contact members on opposite sides of the tube. When current is supplied to demagnetize, or magnetize permanent magnets installed, the tube can selectively be blocked or opened. An external current of substantial value is required in order to operate the unit, and while it is indicated that power consumption is low, there still is a need for external power. The device shown in the '952 patent can be used as a pump as well by alternately magnetizing and demagnetizing the permanent magnets.
U.S. Pat. No. 4,994,019 discloses the use of an active magnet mechanism and appliance for the control of incontinence that must be controlled by external stimuli and must be surgically inserted through significantly invasive surgery. Finally, U.S. Pat. No. 5,509,888 teaches the use of magnetorheological fluids housed in a chamber and which react within an applied magnetic flux to radically change their viscosity and other rheological properties to form an artificial sphincter.
Magnetically controlled plugs have also been advanced for controlling incontinence, and such devices are shown in German Patent Nos. DE2717607 and DE3139811.
From the foregoing discussion, it will be appreciated that many approaches and treatments have been proposed to cure or relieve conditions of urinary incontinence. While some of these approaches have enjoyed modest success, relief has been for the most part, only temporary in those patients where success is noted. Thus, there remains a continuing need for improving treatment of such urological disorders.